There have been few disclosures of the technique for effectively recovering Rh from such solution containing noble metals such as Rh.
However, Japanese Patent Application Laid-Open Publication No. 2005-97695 “Mutual separation method of platinum group element” discloses a mutual separation method of platinum group elements such as Pd, Pt, Ir and Rh.
This publication does not disclose any examples in which the solution contains Ag. Therefore, the publication does not disclose any troubles, which could occur during a recovery process of Rh using an extracting agent.
The inventors have found out that when Rh is to be recovered from a solution containing Ag, because of poor phase-separation property, Rh cannot be effectively recovered. Further, it has been found that impurities such as Fe and Pb remain in the post-extraction solution, thereby Rh recovery cannot be conducted effectively.